The Lawson criterion outlines the specific physical conditions that must be met for a nuclear fusion reactor to produce more energy than it consumes—a state known as net energy gain or break-even.
Core Idea:
It relates three crucial parameters of a fusion plasma:
- Temperature (how hot the plasma is),
- Density (how many fusion fuel particles are packed together), and
- Confinement time (how long the plasma stays hot and dense enough to allow fusion to occur).
Together, these determine whether the energy produced by fusion reactions exceeds the energy lost from the system.
Importance:
- It is not a single value, but rather a relationship: higher temperatures may allow for shorter confinement times, or higher densities can make up for lower temperatures.
- For deuterium-tritium (D-T) fusion, which is the most feasible reaction currently, the Lawson criterion gives a minimum threshold product of density and confinement time.
Applications:
- Used to evaluate the performance of fusion devices like tokamaks, stellarators, and inertial confinement systems.
- Helps engineers and physicists benchmark fusion experiments and assess progress toward practical fusion energy.